This invention relates to apparatus for supporting a stack of veneer sheets in such a manner that the top of a stack supported is maintained at substantially a predetermined level during the process of removing sheets from the top of the stack (which has the effect of diminishing the height of the stack). The apparatus includes means referred to herein as accumulator means, functioning to support the remnant of a stack from which most of the sheets have been removed with the top of such stack remnant at the desired predetermined level, freeing platform structure which formerly supported the stack whereby such may be supplied with a new stack of sheets. After removal of all sheets in the stack remnant, the top of the newly deposited stack may immediately be placed at the predetermined height desired.
In a more specific sense, the invention concerns apparatus for feeding veneer sheets to a dryer which includes an elevated, power-driven, substantially horizontal pinch roll mechanism, having upper and lower rolls spaced apart from each other to provide a space into which the lead ends of veneer sheets may be placed and movable toward each other to initiate forward motion of such sheets into the dryer. A stack supporting apparatus of the type earlier described is provided in conjunction with such pinch roll mechanism, which may be operated to maintain the top of a stack supported on the apparatus at substantially the level of such pinch roll mechanism. Thus, in feeding sheets, the operator pushes sheets from the top of the stack forwardly to place their ends between the rolls of the pinch roll mechanism, with such rolls separated. In this condition, the sheets which have been partially introduced to the pinch roll mechanism are partially supported by the lower roll in the pinch roll mechanism, and by the stack of veneer sheets which supports the rear ends of the sheets. With the rolls brought together, the sheets progress forwardly, after which the rolls are separated to enable the operation to be repeated.
When the stack of sheets supported on the apparatus becomes nearly depleted, the accumulator means above-described is actuated whereby the remnant of the stack may be maintained at proper elevation for the continued feeding of sheets between the pinch roll mechanism. This support is independent of the platform which formerly supported the stack, which is free to be lowered to receive a new stack of sheets. With a new stack deposited on the platform, and under the remnant of a stack of sheets in the process of being fed to the pinch rolls, the platform may be raised, whereby on the stack remnant becoming fully depleted of sheets, the new stack of sheets is immediately in position to continue the feeding of sheets between the pinch rolls.
In U.S. Pat. No. 2,876,009 issued to Otto G. Jeddeloh, there is disclosed a sheet loading mechanism for a multi-deck conveyor, more specifically a veneer dryer, which includes a pinch roll mechanism comprising a lower, smooth-surfaced steel roll, and an upper, rubber-surfaced roll, which upper roll is movable toward and away from the lower roll. An elevatable platform on the feed side of this pinch roll mechanism supports a stack of veneer sheets with the top of such stack maintained substantially at the height of the pinch roll mechanism. An operator moves sheets from the top of the stack to place ends of the sheets over the lower steel roll, with the rolls of the pinch roll mechanism separated. The rolls of the pinch roll mechanism then move together to initiate forward movement of such sheets into the dryer. No provision, however, is made for holding a nearly depleted stack of veneer sheets with the top of such nearly depleted stack at proper level for feeding between the pinch rolls and with such nearly depleted stack held independently of the platform. As a consequence, all the sheets from a stack supported on the platform must be fed into the dryer before the platform can be reloaded. During reloading of the platform, which requires lowering of the platform and movement of a new stack thereon, followed by partial raising of the platform properly to adjust the height of the top of the stack, no feeding of veneer sheets can occur and the dryer, in effect, is unused. With the cost of operating a veneer dryer being substantial, obviously substantial savings are realized if such periods of dryer non-use are eliminated.
Generally, therefore, an object of this invention is to provide apparatus for supporting a stack of veneer sheets which accommodates the recharging of a new stack of veneer sheets on a platform in the apparatus without interuption of the removal of sheets from the top of a stack remnant supported in the apparatus.
Another object of the invention is to provide apparatus for feeding veneer sheets into a dryer, which provides an uninterrupted supply of sheets at a predetermined elevation, ready for movement of sheets from the supply periodically between pinch rolls adapted to initiate movement of such sheets into the dryer.
An important feature of the apparatus of the invention is that is requires substantially no more space in a dryer installation than constructions that are presently in use which are devoid of the capability of recharging a stack while the feed of veneer sheets into the dryer continues.
Yet another object of the invention is to provide a stack supporting apparatus as above-described characterized by a construction which is relatively free of moving parts exposed in such a manner as to be hazardous to operating personnel.
More specifically, an object of the invention is to provide apparatus for supporting a stack of sheets, such as veneer sheets, which includes an elevatable platform adapted to be charged with a new stack of sheets in a lowered position and then to be raised to place the top of the stack at a desired level, and an accumulator means engagable with the underside of a partially depleted stack independently of the platform, whereby such may be lowered to be charged with a new stack of sheets. Specifically, such accumulator means comprises hoist bars carried by the platform actuatable to lift a partially depleted stack of sheets from the support plane of the platform, and holding arms or bars that are actuatable to move from an inoperative position to an operative position wherein such come up underneath the remnant stack lifted by the hoist bars. The platform is lowerable after the holding arms have been properly positioned, to leave the stack remnant entirely supported by the holding arms. With lowering of the platform, such may be charged with a new stack of veneer.
The invention further contemplates guide structure for the holding arms, with guideways provided for each of the opposite ends of the arms, and powered means for moving such arms along the paths defined by such guideways.